1. Field of the Invention
The invention relates generally to miniature electromagnetic switches for microwave systems. More specifically, the invention relates to a miniature double-throw electromagnetic microwave switch capable of operation in three different states.
2. Description of the Prior Art
Switches are a basic building block of communication electronics and can find many applications in telecommunications. They are widely used for telecommunications applications such as signal routing, redundancy switching, impedance matching networks and adjustable gain amplifiers. Mechanical relay, PIN diode and FET are the common microwave switches. Mechanical relays offer the benefits of low insertion loss, large off-state isolation, and high power handling capabilities. However, they consume a lot of power and are bulky, heavy and slow. Semiconductor switches such as PIN diode and FET provide much faster switching speed and smaller size and weight but are inferior in insertion loss, isolation and power handling capabilities than mechanical relays.
Microwave switches providing the advantageous properties of both the mechanical relay and semiconductor switch are then highly desirable, especially for space, airborne and mobile telecommunications applications. Micromachining technologies promise to enable the fabrication of such switches, i.e., switches with the high microwave performance of mechanical switches but also with the small size, weight and power consumption of semiconductor switches. Furthermore, conventional microelectronics fabrication processes are usually used for micromachining, making the integration of such miniature switches with other active electronics possible.
In U.S. patent application Ser. No. 09/131,594 entitled `Miniature Electromagnetic Microwave Switches and Switch Arrays` filed on Aug. 10, 1998 by the same inventors, now U.S. Pat. No. 6,016,092 single-throw micro electromagnetic switches in a coplanar waveguide, microstrip or stripline form were described. A double-throw switch in a stripline form was also described. In this invention, miniature double-throw electromagnetic switches on dielectric substrates in a microstrip form and with controlled magnetization are disclosed. These double-throw switches are useful in many applications for effective switching and routing of microwave signals.